It has been the long-felt need of the independent local telephone company (hereafter "telephone company" or "operating company") or telephone service provider (hereafter "service provider") to maximize the utilization of a subscriber's high-capacity telephone line (that is, at least 1.544 Mbps or DS1) by being able to have the capability of providing automated diagnostics of the high-capacity digital transmission path through customer premises equipment of the end-user (or "subscriber" used interchangeably hereinafter) from either a remote location, or the location of the end-user, as well as be able to conduct a facility loop-back test from a remote location, or location of the end-user, that would be able to test the portion of the transmission circuit that is situated between the particular central office and the customer premises equipment of the end-user. This is accomplished by allowing the network control center to be able to initiate facility loop-back tests by the sending of in-band or out-of-band command codes (depending on the associated framing) to remote customer premises equipment over the packet switched network, the codes being compatible with the specific protocol associated with high-capacity digital transmission presentations. Additionally, it has always been a need of the telephone company or service provider to have the technical capability to conduct continuous nonintrusive diagnostics performance monitoring with respect to multiple key variables or characteristics, thereafter store the relevant historical performance data (in associated memory or otherwise) with respect to the digital circuit for a period of time, and then be able to recall this historical performance data whenever a service disruption has been reported by the end-user, in order to determine (i) what the specific problem was that the end-user experienced, (ii) where in the transmission path was the problem fault located, and (iii) what could be done in the form of preventive maintenance in order not to re-experience or repeat the problem again in the future.
From the end-user's viewpoint, following divestiture, in as much as there may be more than a single telephone service provider in a given geographic area or market (for example, an independent local telephone company providing local telephone service and the independent long-distance carrier providing long-distance telephone service), there has resulted an increased need to be able to actually define where a given equipment problem or circuit fault or out-of-service problem is physically located, as end-users have generally assumed more of the responsibility for the maintenance of customer premises equipment that is located at the location of the end-user. This has resulted in a need for automated diagnostics that are capable of testing the portion of the telephone service for which the service provider or telephone company is responsible, as well as being able to pinpoint the particular problem fault or disruption in service that the end-user had experienced which has resulted in the customer premises equipment being out of service. If the service provider or telephone company can find the trouble and localize the fault or problem circuit to reside physically within the customer premises equipment at the location of the end-user (and hence beyond the perpetual warranty of the service provider or telephone company), the end-user will have to decide whether or not to invest the necessary funds to acquire customer premises equipment of greater reliability and improved quality with respect to obtaining the benefit of continuous and reliable performance of its customer premises equipment with an appropriate duty or life cycle.
Specifically, high-capacity digital services (HCDS), with associated transmission rates of at least 1.544 Mbps, represent a major revenue opportunity for the telephone company or service providers, and consequently, have grown rapidly in recent years. To realize the full potential of these service offerings, the service provider or telephone company must provide a quality of service that is sufficient to dissuade end-users or customers from selecting the bypass-type private commercial networks, or other alternatives, to the available data services provided by the service provider or telephone company. Digital transmission errors occurring in short bursts are a common complaint of end-users who use any type of high-capacity digital services and are the type of transmission errors that are difficult to localize with after-the-fact, the out-of-service type of portable test equipment or methods that are usually used by maintenance personnel who travel to the location of the end-user location where the HCDS-facility troubleshooting is then conducted (by taking the specific digital circuit out-of-service for purposes of diagnostics testing). It would be advantageous to be able to test and evaluate the overall digital circuit integrity to determine if the problem fault resides in the DS1 facility side of the circuit or the side of the circuit that has the customer premises equipment connected thereto without the need to dispatch maintenance technicians to the location of the end-user, or without the need to take the specific digital circuit out-of-service.
Preventative maintenance in the form of performance diagnostic testing and circuit monitoring has become a standard part of the preventative maintenance and circuit trouble-shooting procedures for determining or assessing continuity of the DS1 communications path between the central office and the customer premises equipment at the site of the end-user. Since equipment of the prior art design and construction does not provide any information or knowledge with respect to how bad the HCDS service has degraded at the network interface, this has usually required a technician to take a portable test unit to a designated service area, or number of designated service areas in the DS1 transmission span, in order to be able to conduct suitable testing and maintenance of the DS1 transmission spans by conducting a loop-back test to analyze and test the specific suspect digital circuit. Once the DS1 circuit is looped-up, the overall circuit integrity can be evaluated to determine if the problem fault resides in the DS1 facility or in the customer premises equipment without the need to dispatch technicians to the location of the end-user.
Furthermore, with the present facility loop-back equipment of the prior art design and construction, there was no capability to retrieve historical information relative to performance of the HCDS circuit. Specifically, the facility loop-back equipment of the prior art design and construction utilized the embedded maintenance channel of the 4 Kbps facility data link to communicate only in-band loop-up or loop-down command codes (thereby either looping-up or looping-down the facility loop-back interface for purposes of conducting a facility loop-back test). It would be advantageous to be able to use the embedded maintenance channel of the 4 Kbps facility data link to additionally communicate with the facility loop-back interface to download performance data that has been stored relative to a specific digital communications path, without interfering with the ability of the facility loop-back interface to receive its respect loop-up or loop-down command codes. Accordingly, it would be advantageous to be able to loop-up the DS1 circuit from any remote test location has access to the DS1 circuit and be able to obtain relevant historical performance data regarding the nonintrusive monitoring of the recent performance of the DS1 circuit for both directions of transmission in order to evaluate overall transmission span integrity for HCDS and similar services utilizing a 1.544 mbps DS1 facility which may be extended to an end-user location. Furthermore, the telephone company or service provider would like to be able to determine whether the facility signal is good, or bad, and if bad, to thereafter be able to sectionalize the problem fault in the circuit to either the receive circuit path to the end-user, or to the transmit circuit path from the end-user.
The present competitive commercial environment requires the telephone company or service provider to minimize burdensome costs associated with trouble-shooting interconnection equipment, with respect to determining if the trouble and/or fault operation can be attributable to either the local telephone equipment, contracted service, or remote customer premises equipment. This may lead to disputes in discovering and assessing where the particular problem fault is physically located and who should pay for or incur the eventual cost to correct or repair the problem fault. It would be desirable to have a cost-effective means for facilitating rapid detection of error bursts and immediate trouble shooting sectionalization of the problem fault.
In the future, it will also be advantageous to have a facility loop-back interface that will be compatible with present high-capacity digital signals and networks, and be upward compatible with expected future ISDN (integrated services digital networks, which provide for simultaneous audio, video and data) with respect to standard and/or unique in-band and/or out-of-band signaling protocols that will be used or with respect to the digital transmission rates that will be available for high-capacity digital network signals and networks. Early generation products pertaining to facility loop-back interfaces of the prior art design and construction have often lacked technical compatibility with one or more of the state-of-the-art high-capacity digital signals or networks, or have lacked the ability to have build-in flexibility to accomplish these necessary objectives.
A design for a microprocessor-based, full duplex facility loop-back test, diagnostics and maintenance system having an intelligent diagnostics interface which is capable of supporting LAP-B protocol, or any given protocol with simple reprogramming of the central microprocessor, and having specified maintenance capabilities for testing and continuous nonintrusive diagnostics of multiple on-line performance capabilities of both DS1 facilities and customer premise equipment, is lacking in the art. Furthermore, the ability to conduct facility loop-back testing for the DS1 communications path continuity through the customer premises equipment at the location of the network interface for the end-user, remotely from a centralized network location of the service provider or telephone company without having to dispatch a technician, is additionally lacking in the art.